Human dentition Dr. Hazem Al Ajrami First Year in Dentistry First Semester Al-Azhar University - Gaza Lama El Banna

1. 11

2. 22
College of DentistryCollege of Dentistry
Human Dentition IIHuman Dentition II
Deciduous Incisors & CaninesDeciduous Incisors & Canines
Dr. Hazem Al AjramiDr. Hazem Al Ajrami

3. They are the predecessors for the permanentThey are the predecessors for the permanent
incisors.incisors.
Apart from general differences in size and color,Apart from general differences in size and color,
etc., the deciduous incisors are similar to theiretc., the deciduous incisors are similar to their
permanent successors, the crowns are, however,permanent successors, the crowns are, however,
more bulbous.more bulbous.
33
Deciduous IncisorsDeciduous Incisors

5. In brief the deciduous incisors are characterizedIn brief the deciduous incisors are characterized
by:by:
Maxillary incisors:Maxillary incisors:
 The crowns are short and wide.The crowns are short and wide.
 The labial and lingual surfaces are trapezoidal inThe labial and lingual surfaces are trapezoidal in
shape with the shortest of the uneven sides isshape with the shortest of the uneven sides is
present at the cervix which appears morepresent at the cervix which appears more
constricted than in the permanent teeth.constricted than in the permanent teeth.
55

6. 66

7.  The lingual surface exhibits a prominentThe lingual surface exhibits a prominent
cingulum and marginal ridges as well as acingulum and marginal ridges as well as a
deep lingual fossa.deep lingual fossa.
 The proximal surfaces are triangular in shapeThe proximal surfaces are triangular in shape
with a pointed incisal edge that lies on the longwith a pointed incisal edge that lies on the long
axis of the tooth.axis of the tooth.
 The incisal angels of are rounded (except forThe incisal angels of are rounded (except for
the mesio-incisal angle of the maxillary centralthe mesio-incisal angle of the maxillary central
incisor, which is sharp).incisor, which is sharp).
 The roots are long and bulky.The roots are long and bulky.
77

8. Mandibular incisors:Mandibular incisors:
 The crowns are very small, narrow and long.The crowns are very small, narrow and long.
 The labial and lingual surfaces are trapezoid inThe labial and lingual surfaces are trapezoid in
shape.shape.
 The lingual surface of mandibular incisors hasThe lingual surface of mandibular incisors has
poorly developed cingulum, lingual ridges andpoorly developed cingulum, lingual ridges and
lingual fossa.lingual fossa.
88

9. 99

10.  The proximal surfaces are triangular in shapeThe proximal surfaces are triangular in shape
with an incisal edge lying on the long axis ofwith an incisal edge lying on the long axis of
the tooth (in contrast to the incisal edge of thethe tooth (in contrast to the incisal edge of the
permanent lower incisors that is inclinedpermanent lower incisors that is inclined
lingually).lingually).
 The incisal angles are sharp.The incisal angles are sharp.
 The roots of mandibular incisors are long, thinThe roots of mandibular incisors are long, thin
and straight.and straight.
1010

11. Deciduous maxillary canine:Deciduous maxillary canine:
 It is the predecessor for the maxillary permanentIt is the predecessor for the maxillary permanent
canine.canine.
 The maxillary deciduous canine is the thirdThe maxillary deciduous canine is the third
tooth from the midline of the maxilla. Althoughtooth from the midline of the maxilla. Although
the overall size of the tooth is smaller, it isthe overall size of the tooth is smaller, it is
sometimes easily confused with the permanentsometimes easily confused with the permanent
canine because of its large crown and thickcanine because of its large crown and thick
labiolingual proportions.labiolingual proportions.
1111

13. 1313

14. Labial aspect:Labial aspect:
 The crown outline form: trapezoid with theThe crown outline form: trapezoid with the
shortest of the uneven sides is presentshortest of the uneven sides is present
cervically. The crown may be as wide as it iscervically. The crown may be as wide as it is
long and is constricted at the cervix more thanlong and is constricted at the cervix more than
the incisors.the incisors.
 The mesial and distal outlines are convex. TheThe mesial and distal outlines are convex. The
mesial and distal contact areas are near themesial and distal contact areas are near the
center of the crown cervico-occlusally, withcenter of the crown cervico-occlusally, with
the mesial one more cervically located.the mesial one more cervically located.
1414

16.  Incisal outline: it has a sharp and long cuspIncisal outline: it has a sharp and long cusp
with the two cusp ridges meeting at an acutewith the two cusp ridges meeting at an acute
angle (less than 90). The mesial cusp slope isangle (less than 90). The mesial cusp slope is
longer than the distal one (opposite of thelonger than the distal one (opposite of the
permanent canine).permanent canine).
 The labial surface is strongly convexThe labial surface is strongly convex
particularly at the cervical one third. Aparticularly at the cervical one third. A
longitudinal ridge (labial ridge) connects thelongitudinal ridge (labial ridge) connects the
cervical ridge with the cusp tip; shallowcervical ridge with the cusp tip; shallow
grooves lie on either side.grooves lie on either side.
1616

17.  The cervical line is nearly straight.The cervical line is nearly straight.
 The root would be longest of the deciduousThe root would be longest of the deciduous
teeth (it may be more than twice the crownteeth (it may be more than twice the crown
length) and would taper evenly to a blunt apex.length) and would taper evenly to a blunt apex.
 Its apical third may be inclined distally.Its apical third may be inclined distally.
1717

19. Lingual aspect:Lingual aspect:
 The crown has a bulky cingulum and well-The crown has a bulky cingulum and well-
developed mesial and distal marginal ridges asdeveloped mesial and distal marginal ridges as
well as cusp ridges. All ridges are lesswell as cusp ridges. All ridges are less
prominent than in the permanent canines.prominent than in the permanent canines.
 The lingual ridge connects the cusp tip and theThe lingual ridge connects the cusp tip and the
cingulum and is situated somewhat distal tocingulum and is situated somewhat distal to
the middle of the tooth.the middle of the tooth.
 On either side of the lingual ridge both aOn either side of the lingual ridge both a
mesial or a distal fossae are present.mesial or a distal fossae are present.
 The root tapers lingually.The root tapers lingually.
1919

21. Mesial and distal aspects:Mesial and distal aspects:
 The crown outline is triangular with the base isThe crown outline is triangular with the base is
present cervically and the apex is at the cusp tip.present cervically and the apex is at the cusp tip.
 The cervical third of the crown is much thickerThe cervical third of the crown is much thicker
than in the deciduous incisors.than in the deciduous incisors.
 Labial outline: there is a prominent labialLabial outline: there is a prominent labial
cervical ridge that appears to bulge and occupycervical ridge that appears to bulge and occupy
the cervical one third.the cervical one third.
2121

23.  The lingual outline below the cingulum is moreThe lingual outline below the cingulum is more
concave than it is on the permanent canines.concave than it is on the permanent canines.
 Incisal outline: the cusp tip is positionedIncisal outline: the cusp tip is positioned
considerably labial to the long axis line.considerably labial to the long axis line.
 The cervical line curves incisally more on theThe cervical line curves incisally more on the
mesial than on the distal side.mesial than on the distal side.
 The root is bulky in its cervical and middle thirds,The root is bulky in its cervical and middle thirds,
tapering most in the apical third.tapering most in the apical third.
2323

24. Incisal aspect:Incisal aspect:
 Outline form: diamond in shape.Outline form: diamond in shape.
 The contour is somewhat angular and tapersThe contour is somewhat angular and tapers
noticeably toward the cingulum (lingualnoticeably toward the cingulum (lingual
convergence).convergence).
 The cusp tip is distal to the center of the crownThe cusp tip is distal to the center of the crown
and the mesial cusp slope is longer than theand the mesial cusp slope is longer than the
distal one.distal one.
 The cingulum is centered mesiodistally.The cingulum is centered mesiodistally.
 The crown is broader labiolingually than theThe crown is broader labiolingually than the
incisors but is still wider mesiodistally thanincisors but is still wider mesiodistally than
labiolingually.labiolingually. 2424

26. Deciduous mandibular canine:Deciduous mandibular canine:
o It is the predecessor for the mandibular permanentIt is the predecessor for the mandibular permanent
canine.canine.
o The mandibular canine crown is may be shorterThe mandibular canine crown is may be shorter
by about 0.5 mm. than the maxillary canine and isby about 0.5 mm. than the maxillary canine and is
narrower mesiodistally. The crown is much longernarrower mesiodistally. The crown is much longer
than it is wide.than it is wide.
2626

27. 2727

28. o The cusp tip may be pointed like an arrow.The cusp tip may be pointed like an arrow.
o The labial surface has a labial ridge and aThe labial surface has a labial ridge and a
cervical ridge that are not quite as pronouncedcervical ridge that are not quite as pronounced
as those found on the maxillary canine.as those found on the maxillary canine.
o The lingual surface has faint marginal ridges,The lingual surface has faint marginal ridges,
an ill developed lingual ridge and usually aan ill developed lingual ridge and usually a
single concavity or lingual fossa.single concavity or lingual fossa.
2828

29. o As in the permanent mandibular canine, theAs in the permanent mandibular canine, the
mesial cusp slope is shorter than the distal cuspmesial cusp slope is shorter than the distal cusp
slope (which is opposite to the maxillaryslope (which is opposite to the maxillary
deciduous canine).deciduous canine).
o The cervical line curves incisally more on theThe cervical line curves incisally more on the
mesial side than on the distal side.mesial side than on the distal side.
o From the incisal aspect the crown has a diamondFrom the incisal aspect the crown has a diamond
shape and is nearly symmetrical, except for theshape and is nearly symmetrical, except for the
mesial position of the cusp tip.mesial position of the cusp tip. 2929

30. o The root is at least 2 mm. shorter than theThe root is at least 2 mm. shorter than the
maxillary canine but tapers more with a moremaxillary canine but tapers more with a more
pointed apex.pointed apex.
o From the proximal view the root is broadFrom the proximal view the root is broad
labiolingually for two thirds of its length,labiolingually for two thirds of its length,
tapering mostly in the apical third.tapering mostly in the apical third.
3030